Aquaponics

Aquaponics edit  Aquaponics combines raising fish (Aquaculture) with growing plants in water (Hydroponics). This is done using no soil in a recycling water system.
Beneficial bacteria convert the ammonia produced by the fish into nitrates which feeds the plants. By absorbing the nitrates, the plants clean the water which is then returned back into the fish tank. As the water falls from the plant rafts back into the fish tank it absorbs oxygen which aerates the water for the fish, plants, and bacteria.
Aquaponics is a way of growing food where there is poor soil, limited space, or shortage of good water. Aquaponics makes it possible to grow more food in less space, using no soil, all while using 90% less water than in ground agriculture. There are several different mothods of Aquaponics systems which allow us to demonstrate, teach, and experiment to find optimal growing infromation to take to the nations. All of our vegetables and herbs grown using Aquaponics are used by our campus cafeteria, and the tilapia we raise are available to staff families. 

Catfish

These catfish were raised from fingerlings and are now more than four years old. We chose them because we wanted a species that could live in very low dissolved-oxygen conditions in a manually operated aquaponics system. These fish have proven capable of living here in our IBC tank without aeration (no airpump w/ diffuser) and have successfully provided a nutrient source for several aquaponics configurations including media bed and NFT.

We learned the hard way that overfeeding promotes disease. Our protocol now is to feed twice per day, only as much as they will eat in 5 minutes so that no uneaten food accumulates on the bottom of the tank. 

Media bed systems

An interesting feature on our media beds is the false bottom design. Another Glenn Martinez inspired configuration the false bottom leaves an empty space under the media. 

Airilift Pump

Airlift pumps, as the name implies, lift water using an air pump instead of a submersible or external water pump. Airlifts save us money and have increased the reliability of our systems. The inventor Glenn Martinez shared his designs with us. We have found them to be well suited to aquaponics for several reasons starting with the fact that they aerate the water while they lift it.

Additional characteristics make these pumps especially well suited to aquaponics. For one, they can handle solids (even gravel) without plugging, burning up, or wearing out. The low-pressure (2-5 psi) air pump that powers the airlift is unaffected by abrasives, fish, or most anything else in the water. 

In some situations, an airlift pump may replace a more energy-hungry water pump. Additionally, an inexpensive replacement diaphragm can extend the life of a good quality air pump to ten or fifteen years making them a potential money-saving alternative to conventional water pumps.

Airlift pumps can be made with basic tools and beginner-level skills from parts available in most stores that sell PVC pipe and fittings. The 35 to 80-watt diaphragm air pumps that power them are widely available in larger cities, often at larger aquarium or pond supply stores and on the internet. Airlifts require an air pump that will produce 5-6 psi for initial startup, then run continually at about 2 psi. A diaphragm pump will do this, other high-volume, low-pressure pumps will not provide the initial pressure needed.

One of the airlift designs uses a "well" that can simply be made from a larger diameter closed-end PVC pipe. This well is typically plumbed into the fish tank or sump. It extends several feet deeper than the tank, effectively making a water column that is as deep as the pipe plus the water depth in the tank. The pipe can be in a hole dug next to the tank or placed off the side of a stand that the tank is supported on. Glenn calls this design a "Pipe-In-A-Pipe Pump". It is most efficient in deeper water. The depth required depends on the diameter of the pipe used, head height and desired flow rate. Ours are operating in from 1 to 1.5 meters of water.

When a well is not practical Glenn's "Burper" style airlift works with a non-spring-loaded, one-way flapper valve. Unlike the Pipe-In-A-Pipe Pump, this Burper pump will completely empty a tank if desired.

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